An Acad Bras Cienc (2020) 92(3): e20190967 DOI 10.1590/0001-3765202020190967 Anais da Academia Brasileira de Ciências | Annals of the Brazilian Academy of Sciences Printed ISSN 0001-3765 I Online ISSN 1678-2690 www.scielo.br/aabc | www.fb.com/aabcjournal BIOLOGICAL SCIENCES Description of the immature stages of Running title: Immature stages of Stenocrates agricola Dechambre & Hardy Stenocrates agricola (Coleoptera: Scarabaeidae: Dynastinae: Academy Section: Biological Cyclocephalini) with redescription of the Sciences adult and discussion of its tribal position MARIO G. IBARRA-POLESEL, JHON C. NEITA-MORENO & BRETT C. RATCLIFFE e20190967 Abstract: The enigmatic genus Stenocrates Burmeister has 52 species that are widely distributed from Mexico to Argentina, but mainly in South America. In the present study, 92 (3) the larva of the third instar and pupa of Stenocrates agricola Dechambre & Hardy, 2004 92(3) are described and illustrated based on specimens from Argentina, this being the first description of immatures for the genus. The adult is also redescribed, significantly expanding the number of characters and providing information on the natural history of this species. In addition, 28 species of Cyclocephalini and 20 species of Pentodontini are morphologically compared, emphasizing the most useful larval characters used among these beetles. Stenocrates agricola shows frequent and common characters of Pentodontini species but scarce (and even absent) characters typical of Cyclocephalini species, including some considered diagnostic for this tribe. Accordingly we consider that the tribal position of Stenocrates remains controversial and more study is needed to clarify the tribal status of Stenocrates. We believe that larval morphology provides important information in systematics studies that can clarify tribal relationships within the Dynastinae. Key words: larva, morphology, pupa, scarab beetle, taxonomy. INTRODUCTION 2015), but only 28 species (≈5.6%) have had larvae formally described (see Table I). Likewise, The larvae of pleurostict Scarabaeidae are Pentodontini is comprised of 151 species in the commonly known as “white grubs”, and some New World (Morón 2017), but the larvae of only species are considered important crop pests, 20 species have been described (≈13.2%). Despite mainly due to the rhizophagous habit of their this, research interest in immature stages has larvae (Ratcliffe & Cave 2006, Ritcher 1966, increased in recent times. According to Moore et Rodrigues et al. 2018). In spite of this, taxonomic al. (2018), 80% of the descriptions of larvae and knowledge of the immature stages is scarce pupae of Cyclocephalini were published after worldwide. In the Americas, the subfamily 1990. Dynastinae is divided into the following tribes: In several scarabaeoid studies, larval Cyclocephalini, Pentodontini, Oryctini, Phileurini, characters were used either alone or in Agaocephalini, and Dynastini (Ratcliffe & combination with adult characters to establish Cave 2006). In the New World, Cyclocephalini natural groups and phylogenies (Micó et al. comprises ca. 500 species (Ratcliffe & Cave 2008). Since the larval morphology can reveal An Acad Bras Cienc (2020) 92(3) MARIO G. IBARRA-POLESEL, JHON C. NEITA-MORENO & BRETT C. RATCLIFFE IMMATURE STAGES OF Stenocrates agricola Table I. Described third instars of Cyclocephalini and Pentodontini species. *1 - cited as Cyclocephala abrupta Casey, 1863 (junior synonym) by Ritcher (1966); *2 - cited as C. immaculate (Olivier, 1789) (junior synonym) by Ritcher (1966); *3 - cited as Bothynus gibbosus (De Geer, 1774) (new combination) by Ritcher (1966); *4 - cited as Ligyrus gianucai Dechambre & Lumaret (1985) (junior synonym) by Neita & Ratcliffe (2017); *5 - cited as Cheiroplatys pyriformis (LeConte, 1847) (junior synonym) by Ritcher (1966). Cyclocephalini species References Pupa Ancognatha manca (LeConte, 1866) Ritcher (1966) No Ancognatha scarabaeoides Erichson, 1847 Vallejo & Morón (2008) Yes Ancognatha sellata Arrow, 1911 Ramirez-Salinas (2004) Yes Ancognatha ustulata Burmeister, 1847 Neita-Moreno & Morón (2008) Yes Aspidolea singularis Bates, 1888 Neita-Moreno et al. (2007) Yes Cyclocephala barrerai Martínez, 1969 Morón et al. (2014) No Cyclocephala borealis Arrow, 1911 Ritcher (1966) No Cyclocephala celata Dechambre, 1980 Souza et al. (2014b) Yes Cyclocephala comata Bates, 1888 Garcia et al. (2009) No Cyclocephala distincta Burmeister, 1847 Souza et al. (2014a) Yes Cyclocephala fasciolata Bates, 1888 Morón et al. (2014) No Cyclocephala fulgurata Burmeister, 1847 Bran et al. (2006) Yes Cyclocephala gregaria Heyne & Taschenberg, 1908 Bran et al. (2006) Yes Cyclocephala jalapensis Casey, 1915 Morón et al. (2014) No Cyclocephala longula LeConte, 1863 *1 Ritcher (1966) No Morón et al. (2014), Bran et al. (2006), Cyclocephala lunulata Burmeister, 1847 Yes Stechauner & Pardo-Locarno (2010) Cyclocephala lurida Bland, 1863 *2 Ritcher (1966) No Cyclocephala melanocephala (Fabricius, 1775) Rodriguez et al. (2018) Yes Cyclocephala paraguayensis Arrow, 1903 Albuquerque et al. (2014) Yes Cyclocephala parallela (Casey, 1915) Gordon & Anderson (1981) No Cyclocephala pasadenae (Casey, 1915) Ritcher (1966) No Cyclocephala signaticollis Burmeister, 1847 Morelli (1991) Yes Cyclocephala sinaloae Howden & Endrödi, 1966 Morón et al. (2014) No Cyclocephala tucumana Bréthes, 1904 Fuhrmann et al. (2019) Yes Dyscinetus dubius (Olivier, 1789) Neita-Moreno & Yepes (2011) Yes Dyscinetus morator (Fabricius 1789) Ritcher (1966) No Dyscinetus rugifrons (Burmeister, 1847) Vincini et al. (2000) Yes Stenocrates agricola Dechambre & Hardy, 2004 present publication Yes Pentodontini species References Pupa Aphonus castaneus (Melsheimer, 1845) Ritcher (1966) No Aphonus densicauda Casey 1915 Ritcher (1966) No Aphonus tridentatus (Say, 1823) Ritcher (1966) No Bothynus medon (Germar, 1824) Pereira et al. (2013) No An Acad Bras Cienc (2020) 92(3) e20190967 2 | 26 MARIO G. IBARRA-POLESEL, JHON C. NEITA-MORENO & BRETT C. RATCLIFFE IMMATURE STAGES OF Stenocrates agricola Table I. Continuation Pentodontini species References Pupa Coscinocephalus cribrifrons (Schaeffer, 1906) Morón & Deloya (1991) Yes Coscinocephalus tepehuanus Prell, 1936 Morón & Ratcliffe (1996) Yes Euetheola humilis rugiceps (LeConte, 1856) Ritcher (1966) No Ligyrus (Ligyrodes) relictus (Say, 1825) Ritcher (1966) No Ligyrus (Ligyrodes) sallei Bates, 1888 Ramírez-Salinas et al. (2004) Yes Ligyrus (Ligyrus) gibbosus (DeGeer, 1774) *3 Ritcher (1966) No Ligyrus (Ligyrus) nasutus (Burmeister, 1847) Ramírez-Salinas et al. (2010) Yes Ligyrus (Ligyrus) rubripes (Boheman, 1858) *4 Dechambre & Lumaret (1985) No Neoryctes galapagoensis (Waterhouse, 1845) Lumaret (1991) No Orizabus isodonoides Fairmaire, 1878 Morón (1976) No Orizabus pyriformis (LeConte, 1847) *5 Ritcher (1966) No Orizabus brevicollis Prell, 1914 Morón & Deloya (1991) No Oxygrylius ruginasus (LeConte, 1856) Ritcher (1966) No Tomarus subtropicus (Blatchley 1922) Gordon & Anderson (1981) No Philoscaptus bonariensis (Burmeister, 1847) Morelli (1997) Yes Saccharoscaptus laminifer (Dechambre, 1979) Morón (2017) No diagnostic characters that are informative at & Moore 2018, Ratcliffe & Cave 2017). There are different taxonomic levels, some provide more a few studies that, based on larval characters, reliable information than adult morphology have transferred from one tribe to another alone on phylogenetic relationships of taxa some taxonomically problematic genera, e.g., because of the constancy of character states Platyphileurus Ohaus was transferred from (Micó et al. 2008, Ritcher 1966, Sípek et al. 2009, Phileurini to Oryctini by Albertoni et al. (2014); Verdú et al. 2004). Scatimus Erichson and Heliocopris Hope from With regard to the current classification at Coprina to Dichotomiina by Edmonds & Halffter the tribal level of Dynastinae, some authors (1978); and Coscinocephalus Prell was transferred believe there are problems due to doubts from Cylcocephalini to Pentodontini by Morón & about the characters distinguishing each Ratcliffe (1996). Others were transferred based on of the tribes (Albertoni et al. 2014, Clark 2011, adult characters [Parapucaya Prell and Pucaya López-García et al. 2015, Morón & Ratcliffe 1996, Ohaus were transferred from Pentodontini to Ratcliffe & Cave 2006, 2017). Some tribes that Cylcocephalini by Paucar-Cabrera & Moore are sometimes separated by a unique, variable (2018) and Acrobolbia Ohaus from Rutelinae to (or transition) character that is unreliable for Cyclocephalini by Jameson et al. (2002)]. grouping taxa at the tribal level (Ratcliffe & Cave The genus Stenocrates Burmeister 2015, 2017). Some specialists question whether (Dynastinae: Cyclocephalini) comprises 52 the Cylcocephalini and Pentodontini are species distributed from Mexico to Argentina, monophyletic clades (Albertoni et al. 2014, Clark with most occurring in South America (except 2011, López-García et al. 2015, Paucar-Cabrera Chile), and one species is known from the West An Acad Bras Cienc (2020) 92(3) e20190967 3 | 26 MARIO G. IBARRA-POLESEL, JHON C. NEITA-MORENO & BRETT C. RATCLIFFE IMMATURE STAGES OF Stenocrates agricola Indies (Jamaica) (Moore et al. 2018, Ratcliffe Taking into account the unknown immature & Figueroa 2018). This is possibly the most stages for Stenocrates, the brief description of difficult Dynastinae in the Americas with which the adult of S. agricola, the lack of information to work (Ratcliffe & Cave 2015). Most of the about its life history, and the importance of species are